Polyiso Insulation

[Mancino]

I found some reclaimed 1.5" foil faced polyiso insulation for sale. Guy has 40 sheets for $450...looks to be in good shape. Few dings and dents, but looks good. He says it came from an office space he tore down.

Assuming it hasn't absorbed any water, is this stuff still good if it's old? And is that price any good? I'm thinking of buying it for my pole barn walls. It's almost exactly how much I need too.

 

[theoldwizard1]

Yes, it is good ! Poly-iso is one of the best "solid" insulations around, even used.

I can not tell you it that is a good price.

 

[Oregon rock crusher]

Polyiso is easy to install and provides excellent 'R' value / inch. I found a large lot of used sheets several years ago and did my whole shop. Try and get the screws and plates with it if you can. I paid a bit less at about $8.00 / 2" 4X8 sheet but the seller was motivated. I even cut them into panels to insulate the doors and the difference in comfort is dramatic. Ed.

 

[ambenz]

Shouldn't be an issue that the product is old.
The stuff doesn't hold moisture.
As robust as Styrofoam!
The price they are offering is less than 1/2 the price of new sheets.
I use these on my ceiling in the garage, works wonderful!
I recommend you get what you need.

 

[dutchgray]

We use ridiculous quantities of that type of insulation over here, its good stuff, usually cut it on a table saw, not unusual to put 150mm between rafters or 100mm over the top, last house I built had 80mm in the cavity between the two masonry skins.

 

[tatra]

Interesting first paragraph about it loosing r value the colder it gets. First google reference I started reading . I always thought this was the best out there .

http://www.ecohome.net/guide/polyisocyanurate-foam-hot-new-building-product-learn-use

 

[-Brent-]

If you're buying used, try to get a better deal. Here's why:

Polyiso will lose R-value over time because it loses the gas trapped in the cells. The long term thermal resistance of Polyiso decreases as it gasses out. The "long term" in the LTTR testing is 15 years since that's the commercial average for roofing and to which the insulation companies apply their standards. It doesn't matter when it comes to roofing because when the life of a roof is up, it's all torn up and replaced - insulation included.

There's no public data that shows true results of how fast the gas is lost in the cells (and replaced with air) but it is significant enough that EVERY manufacturer keeps that data secret. I've seen data by a client that shows about 1.5 R value loss in 5 years and since the aging method is artificial it's really hard to know how steep the losses are over 10. For certain, as long as it's losing gas, the R-value is decreasing. There is plenty of data on the Internet to support the 5-year loss claims, as well.

If you're already in the market for used materials, this may not be a big deal, but if you're planning to be in the place for 20+ years, then it could be something to think about.

 

[Mancino]

Interesting read, tatra....If it's true, I've never heard this. Makes me wonder if I should just wait and put XPS between the perlins instead.

It's so confusing to read all this information. I feel like I get more confused what to use the more I read.

 

[Mancino]

Also good info, Brent. I don't mind spending some money on insulation, so I'd consider spray foam but I don't want to directly spray it on the metal. I may have to rethink my plan for insulation...Or just focus on concrete for now.

 

[-Brent-]

Oh, and I agree with the comments in the above article about the foil vapor barrier. It's also a good radiant barrier. If those sheets are double-sided foil find out the age of it and make him an offer that reflects your knowledge.

Seriously, I don't think you should be scared of it, just don't think it's the r-value it is. Hell, it's usually not the r-value claimed right out of the manufacturer.

 

[toyotadriver]

Polyiso does lose R value and the R value is believed to be less than stated when you are trying to insulate from cold.

However, any insulation is better than no insulation. If I got a good deal on polyiso, I wouldn't hesitate to use it.

That's about $11.50 per sheet. New XPS 1.5 inch is over $20 per sheet last I checked.

I'd offer him $350 for the lot and be happy to settle at $400.

 

[theoldwizard1]

My daughter's father-in-law is a licensed energy consultant/inspector. He used reclaim poly-iso on the house he built last year.

 

[Billy Jack]

30 years ago, I bought a brick house built in the 60's, that had the entire first story made of concrete block. The builder just carried the foundation block up to the second floor level and raised stud walls from there. First floor had furring strips attached to the block, then drywall with no insulation. Cold enough to be unusable in winter. I pulled down the drywall, cut 3/4" Polyiso carefully to fit between the furring strips, then laid another layer over the furring strips, taped all the seams and attached new drywall with 1 3/4" screws. Room was toasty warm after that. I was only there for 8 more years, but I noticed no decline in insulative properties.

Bill

 

[glen66]

Finishing up my shop right now with the Owens Corning 3" roofing insulation foam board, used spray foam to attach to the walls, great adhesive by the way, foamed and caulked all **** edges and painted. Looks awesome, no dust/dirt blowing in and heating/cooling is awesome. I agree if you can get a good price on this it is/will be well worth it in the long run.

 

[ford33]

Does the loss in R-value only apply to Polyiso insulation?
Does it apply to other solid foam insulation products?
I learned something new today.

 

[toyotadriver]

Does the loss in R-value only apply to Polyiso insulation?
Does it apply to other solid foam insulation products?
I learned something new today.

Polyiso has the worst R value shift. It's still good insulation. There have been some research that indicates that polyiso's R value drops as the temp drops while XPS and EPS remains the same, high temps or cold temps.